1. Field of the Invention
The invention relates to a method and its associated equipment for raising sunken vessels, specifically small to medium sized ships which are submerged in depths to which human descent for purposes of rigging retrieval gear to the ship is impractical or unsafe. The method and equipment can be employed remotely. The equipment and method involve lifting slings which are levered underneath the hull and then used to mechanically raise the vessel to the surface. It is particularly applicable to vessels which are resting on soft sand or clay ocean, sea, or lake bottoms, where interferences with the equipment as it is deployed underneath the vessel are a minimum.
2. Description of the Related Art
The current art shows equipment, mechanisms, methods and processes for raising a sunken vessel which rely on a wide variety of mechanical and pneumatic means. This prior art includes machines for grappling hulls from the surface, mechanisms for remotely welding lifting mechanisms to the hull, mechanisms for filling sunken hull compartments with air bags, foam and other devices for buoyant re-floatation. In addition, the prior art shows a variety of methods for employing slings to lift vessels directly to the surface where those vessels are then refloated.
A major disadvantage of the prior art is that most of these methods and the equipment employed are complex and expensive to manufacture and use. This restricts the use to the refloatation of large hulls with very valuable cargos such that the salvage value exceeds the very high costs.
A secondary disadvantage is that many of these instruments of salvage are reliant on the use of divers to employ the rigging or other gear and, therefore, their application is inherently restricted to hulls which are submerged in shallow bodies of water. This is particularly true of devices which employ slings to lift the vessel.